^^^Sure there's armor. Not a lot. Maybe more ceremonial than practical. But it's there.
(I'm seeing the Klingon uniforms as being essentially the same from Kruge in TSFS thru the movies up to TNG era).
Down the backside, there is a metal-plated spinal section. Also metal shoulder plates and trim and wrist gauntlets and so on. It varied between Kruge and Klaa and Vixis and Chang and Duras and Konmel and Gowron and Kurn and other warriors.
Unless all those metal parts are *not* armor. What else would you call it?